Recently, in the technical field of rotors, technology, in which a permanent magnet is inserted into a hole portion provided in a rotor core and a liquid resin is filled between the hole portion and the permanent magnet to fix the permanent magnet to the rotor core, has been used. In this technical field, a urethane resin, an epoxy resin, and the like are usually employed as the liquid resin. Such technology is described in, for example, PTL 1.
Furthermore, in PTL 2, an epoxy resin used to encapsulate a motor, and a molded article formed by curing the same are described. It is described that working environment properties, productivity, heat resistance, heat conductivity, solvent resistance, high humidity water resistance, and a low linear expansion coefficient are obtained in the molded article. For this reason, it is thought that the molded article described in PTL 2 is used as a housing of a motor.
Moreover, the rotor described in PTL 3 has a structure where a second hole portion communicating with a first hole portion and positioning along the rotation direction of the rotor is formed on the side of the first hole portion accommodating a permanent magnet. By filling a resin or disposing a spring in the second hole portion, stress that the permanent magnet receives from the side wall of the first hole portion in the rotation direction of the rotor is reduced, which is described as being capable of preventing cracking of the permanent magnet.
Incidentally, as a technique used to fill a liquid resin between the hole portion and the magnet of the rotor core, there exist two techniques, a first-in technique and a coating technique. The first-in technique includes the following steps. First, a liquid resin is filled into a hole portion of a rotor core by a dispenser. Thereafter, a magnet is inserted in the hole portions filled with the liquid resin. The first-in technique is described in PTLs 4 and 5. On the other hand, the coating technique includes the following steps. First, the magnet is coated with the liquid resin with a brush. Then the magnet coated with the liquid resin is inserted in the hole portions of the rotor core. The coating technique is described in PTL 6.
[PTL 1] Japanese Unexamined Patent Application, First Publication No. 2007-236020
[PTL 2] Japanese Unexamined Patent Application, First Publication No. 2009-13213
[PTL 3] Japanese Unexamined Patent Application, First Publication No. 2002-359942
[PTL 4] Japanese Unexamined Patent Application, First Publication No. 2005-304247
[PTL 5] Japanese Unexamined Patent Application, First Publication No. H11-98735
[PTL 6] Japanese Unexamined Patent Application, First Publication No. 2003-199303